Sure, they don’t necessarily need to, but in practice, how could you ensure that? It seems like it opens an opportunity for perverse incentives. If a feature’s enticing enough, it will draw people in and if it’s proprietary, then it would be easy for DetSys to lock people into their version, intentionally or not.
Regarding authors making a source of income, there are other ways companies have used open source to accomplish it, such as providing professional support, to name an example.
If you want to experiment with additions to Nix without upstreaming it, would the resulting fork strictly have to be proprietary? Why not maintain a fork while keeping it open source and just not make an upstream PR? I doubt Lix and Tvix necessarily plan on upstreaming their changes, for instance.
That sounds like a somewhat okay idea on its surface. However, I can’t help but suspect that Determinate Nix would suddenly be declared the reference implementation for such a tool if that were to pass. Could you (or someone else) perhaps alleviate these suspicions?
I would say stripping a very popular and useful feature from Nix and privatizing it is already a huge trade-off. What would the benefits of such a move even be? For people other than DetSys, specifically.
I think I am missing something. What problem is this solving? You mentioned it would make it clear to Nix’s users about the status of flakes, but I do not see how breaking tons of downstream users by removing a widely-used feature and giving control of its further development to a for-profit company is a good way to do that.